Variable delivery pump



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VARIABLE DELIVERY PUMP Origina; File'd Nov. 18, 1929 5 Sheets-Sheet 5 jwventoz WA LTEH FEHHLS;

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Patented- July 17, 1934 VARIABLE DELIVERY PUMP Walter Ferris, Milwaukee, Wis., assignor to .The Oilgear Company, Milwaukee, Wis., a corporation of Wisconsin Application November 18, 1929, Serial No. 407,921

Renewed March 3, 1932 Claims.

This invention relates to variable delivery pumps of the type now in common use for energizing the hydraulic feeds in many forms of machine tools.

55 One object of the present invention is the provision of a new control system for pumps of the type mentioned having certain novel operating characteristics peculiarly suited for certain types of machine tools.

l2 other objects and advantages will appear from the following description of an illustrative embodiment of the present invention.

In the accompanying drawings: I Figure 1 is a front elevation of a variable dislii placement pump equipped with a control mechanism embodying the present invention.

2 is a vertical sectional view taken substantially along the line 2-2 of Fig. 1.

Fig. 3 is a diagrammaticview illustrating the 2d pump and control system.

v Figs. i, 5 and 6 are longitudinal sectional views of a control valve employed in the -system, illustrating three characteristic positions thereof.

Fig. 7 is an aerial sectional view of a. pilot valve taken substantially along the line 77 of Fig. 8.

Fig. 8 is a transverse sectional view on the line 3-3 of Fit; '7.

Figs. 9, 10, and 11 are transverse sectional views on the line 9-9 of Fig. 7, illustrating three characteristic positions thereof.

The pump shown in Figs. 1 and 2 is similar in many respects tothe pump described in the copending' application of John P. Ferris, Serial No. 199,925, filed June 20, 1927, which has now matured into Patent No. 1,753,562, issued April 8,

1930. It comprises a casting 10, supported by a mounting plate 11,' and housing a pair of intermeshing gears 12 and 13 which coact to form a constant displacement gear pump 14 of a .well 49 known type. The gear pump is driven atconstant speed by a shaft 15 journaled in the casting 10 and receives'its supply of liquid-ordinarily oil,

from a-reservoir 16 through a pipe 17 which leads up to one side of the pump housing. The gear pump discharges through a pipe or passage 18.

(Fig. 3) to which a low pr'essu'rereliei valve 19 is connected which determines gear pump pressure.

The shaft 15 also drives a variable displacement pump comprising an impeller cage or ring so as, fixed to and rotatable with the shaft, and a cylinder barrel 21 rotatable upon a pintle 22 and containing a plurality of pistons 23 which coact with the cage 20 in a well known manner to set up a now of liquid through the pintle at a rate dependent upon the relative positions of shaft 15 and pintle 22. The pintle is carried by a pendulum 24 depending from a sleeve 25 rockably supported on a hollow shaft 26 which projects horizontally from the casting 10. The variable displacement pump delivers liquid through the pintle and through connections not shown, into a pipe 27 at a rate dependent upon the position of the pendulum 24. The pump receives liquid through the pipe 18 from the gear pump.- The pendulum 24 isaotuated and controlled by a rotatable cam 28 carried by the pendulum and bearing against a roller 29 carried by a fixed bracket 30. (See Fig. 3.) The cam 28 is rotated through a train of gears 31 on the pendulum actuated by a shaft 32 which extends through the 7 hollow shaft 26 and through the mounting plate 11. The displacement of the variable displacement pump may thus be increased or decreased by rotation of the shaft 32. In this instance the shaft 32 is actuated. and controlled by a hand lever 33 through a rack 34 connected thereto and engaged with a pinion 35 on the shaft. The arrangement is such that with the handlever 33 in the upright position of Fig. 3 the roller 29 engages a low point on the cam 28 and the pintle 22 is 30 concentric with the shaft 15 so that pump dis-= placement is zero, but as the lever is shifted in either direction from this upright position the cam 28 is rotated to thereby shift the pendulum 24 and pintle 22 toward the right into an eccentrio position relative to shaft 15 and thus cause the pump to deliver liquid through pipe 27 at an increasing rate dependent upon the extent of rotation of the cam, but always in the same direction whether lever 33 be moved to the right or to the left of the position shown in Fig. 1.

- The discharge from the variable displacement pump is placed under the control of a valve 36 in the form of a hollow plunger closely fitted within a bore 37 in the mounting plate 11.v (See Figs.

2 to 6.) The opposite ends of the bore are closed by cylindrical end heads 38 and 39 fixed to the side edges of the plate 11 (Fig. 1). The bore contains a group of three annular grooves 40, 41 and 42, and a pair of similar grooves 43 and 44 spaced therefrom. The delivery pipe 27 leading from the pump connects with the intermediate groove 41, and the other grooves of the group are connected to pipes 45 and 46, respectively, which lead to the opposite ends of the motor cylinder 47 to be driven by the pump. Groove 43 1s connected through a pipe 48 with the discharge pipe 18 from the gear pump, and groove 44 is connected through a pipe 49 with the delivery pipe 27 from the variable displacement pump. A check no valve 50 within pipe 49 prevents flow through pipe 49 from pipe 2'7. The bore also contains a relatively wide annular end channel 51 which is always in open communication with the longi tudinal passage 52 in the valve plunger and which also communicates with a pipe 53 which leads to the reservoir 16. A low pressure relief valve 54 within the pipe 53 offers a predetermined resistance to the fiow of liquid therethrough. The valve plunger is provided with two relatively wide heads 55 and 56 both of which contain radial ducts 5'7 and 58, respectively, which communicate with the longitudinal passage 52. Head 55 cooperates with a second relatively wide channel 59 in the bore. The valve plunger is also provided with two narrow end heads 60 and 61 and a third narrow head 62 between heads 60 and 55.

The arrangement is such that with the valve plunger 36 in the intermediate position of Fig. 3, pipe 45 is dead-ended so that piston 47 is blocked against movement in cylinder 4'7, and liquid delivered from the pump through pipe 2'7 is re turned to the reservoir 16 through ducts 58, passage 52, channel 51, pipe 53 and resistance valve 54. The resistance valve 54 maintains a predetermined pressure within those connections. The valve 54, however, set to open at a pressure below that required to open the pressure relief valve 19 so that excess liquid discharged from the gear pump 14 passes through pipe 48, grooves 43 and 44, pipe 49, and check valve 50 to the pipe 27 and thence back to the reservoir 16 through the course just described. For a purpose which will be later described the volumetric capacity of the gear pump 14 is considerably greater than the maximum volumetric capacity of the .variable displacement pump.

When the valve plunger 36 is shifted into the position shown in Fig. 4, pipe 48 is blocked off from pipe 49 by the head 62 so that the pipe 2'7 then receives liquid only from the variable displacement pump. Pipe 45 from the left end of cylinder 4'7 is open to the exhaust pipe 53 through the channel 59, ducts 5'7 and passage 52; and the delivery pipe 2'7 is open to the pipe 46 leading to the right end of cylinder 47 so that the piston 4'7 is driven toward the left at a rate determined by the displacement of the variable displacement pump.

When the valve plunger 36 is shifted into the position shown in Fig. 5. pipe 45 is again connected to the exhaust pipe 53 through the ducts 58 and passage 52 delivery pipe 2'7 is still connected with pipe 46 so that the piston 4'7"continues toward the left; but in this position of the valve plunger pipe 48 is again connected through pipe 49 to the delivery pipe 2'7 so that liquid flowing through pipe 48 from the gear pump 14 is added to the supply from the variable displacement pump to thereby drive the piston 4'7 at an increased speed.

When the valve plunger 36 is shifted into the position of Fig; 6 pipe 48 is again connected through pipe 49 to the delivery pipe 2'7 to increase the flow therein; pipe 46 from the right end of cylinder 47 is connected to the exhaust pipe 53; and delivery pipe 2'7 is connected to the pipe 45 leading to the left end of the cylinder to thereby drive the piston toward the right at a rapid rate.

The valve plunger 36 is actuated and controlled by appropriate means under the control of the lever 33. The means shown have proven entirely satisfactory for the purpose and embodies certain novel and advantageous features.

In this instance the valve plunger is yieldably.

retained in the intermediate position of Fig. 3 by a pair of opposed compression springs 63 and 64, seated in the socketed inner ends of the end heads 38 and 39 and bearing against washers 65 and 66 to yieldably retain the washers against internal shoulders 6'7 and 68 formed in the bore and against the opposite ends of the valve plunger. The shoulders 6'7 and 68 limit the inward movement of the washers and coact therewith to accurately center the valve plunger in this intermediate position. The arrangement is such that when the valve plunger is shifted in either direction from this position one or the other of the springs 63 or 64 is further compressed and tends to return the plunger into this intermediate position.

Two operating stems 69 and '70. fixed to and projecting from the opposite ends of the valve plunger 36 extend into bores '71 and '72 formed in the end heads 38 and 39, respectively. A piston '73 in bore 71 is fixed to the end of stem 69. The other stem 70 projects loosely into a socket '74 formed in a piston '75 in bore '72. The stroke of piston '75 is somewhat less than that of piston 73. Piston 73 is fluid actuated in either directionby pressure transmitted to either end of the bore '71 through pipe 76 or '77, and piston '75 is fluid actuated in one direction only by pressure transmitted through pipe '78. A pipe '79 leading from the inner end of bore '72 connects with the exhaust pipe 53 at a point beyond the resistance valve 54.

Pipes '76, '7'7, and '78 are controlled by a rotary pilot valve 80 actuated and controlled by the shaft 32. As illustrated in Figs. 2 and '7 to 11 this valve comprises a substantially cylindrical plug 81 fixed to the end of the shaft 32 and rotatable within a cylindrical housing 82. The housing 82 is supported by the plug 81 and by a lug 83 which projects upwardly from the casing and is fixed to an appropriate lug 84 projecting from a fixed portion 85 of the pump. The exposed end of the housing 82 is recessed to form an annular chamber 86 closed by a disk 8'7. The disk 8'7 is secured to the end of the plug 81 by a screw 88 and interlocked with the plug by a pin 89 so as to rotate therewith. The annular chamber 86 communicates through a passage 90 the housing with a drain pipe'91 which discharges into the reservoir 16. An annular groove 92 formed in the plug 81 communicates through a port 93 with a pressure pipe 94 connected with the pipe 18 leading from the gear pump 14. Three arcuate chambers 95, 96 and 9'7 are formed in the housing 82. These chambers are disposed in a common plane intermediate the groove 92 and chamber 86. A short longitudinal channel 98 in the plug 81 communicates with the groove 92 and extends into the plane of the arcuate chambers 95, 96 and 97. Two similar channels 99 and 100 in the plug extend from the plane of the arcuate chambers into communication with the chamber 86. Pipe '76 from the left end of bore '71 communicates with the arcuate chamber pipe '77 from the right end of bore '71 communicates with arcuate chamber 9'7; and pipe '78 from the right end of bore '72 communicates with arcuate chamber 96.

The arrangement is such that with the lever 33 in the upright position of Fig. 3 the plug 81 is in the position shown in Figs. '7 and 8 in which position the channel 98 is blocked by the land 101 between the arcuate chambers 95 and 96 so that the pressure pipe 94 is blocked; and with the open to both arcuate chambers 95 and 9'1 so that all three of these chambers and their corresponding pipes 76, 77, and 78 are open to the drain pipe.

91 through chamber 86. The valve plunger 36 thus assumes the intermediate position of Fig. 3. Slight movement of the lever 33 toward the right however is suilicient to bring channel 98 into communication with arcuate chamber 96 and to block communication between chamber 96 and the channel 99 (see Fig. 9). When this occurs pipe 78 is exposed to the pressure in pipe 94 and piston '75 is forced into the left end of bore 72 to thereby shift the valve plunger 36 into the position of Fig. 4, in which position liquid from the variable displacement pump alone is delivered through pipe 27 to theright end of cylinder 47 to drive the piston 47' slowly toward the left. As the lever 33 is shifted further toward the right the displacement or the variable displacement pump is increased in the manner previously explained so as to efiect a graded increase in the travel of piston 47'. This condition continues until further shifting-of the lever '33 to the right brings the valve plug 81 into the position of Fig. 10, in which position channel 99 is cut ofi from arcuate chamber 97, channel 98 communicates with that chamber, and pipe 77 leading to the right end of bore 71 is exposed to the pressure in pipe 94 to thereby shift the valve plunger 36 into the left extreme position of Fig. 5. The discharge from the gear pump is then added to the discharge from the variable displacement pump in the manner previously described, to drive the piston 4'7 rapidly toward the left.

By shifting the lever 33 toward the left from the neutral position of Fig. 3, the valve-plug 81 is rotated counter-clockwise into the position of Fig. 11 in which position chambers 96 and 97 are open to the channels 99 and 100, so that the pipes 78 and 7? are both open to the drain pipe 91, and channel 98 is open to chamber 95, so that the pipe 76 leading to the left end of bore 71 is exposed to the pressure in pipe 94 and the piston 73 moves toward the right to shift the valve plunger 36 into the right extreme position of Fig. 6. The piston 47' is then driven rapidly toward the right under the action of the liquid supplied through pipes 27 and 45 from both the variable displacement pump and the gear pump in the manner previously explained.

Various changes may be made in the embodiment of the invention hereinabove specifically described without departing from or sacrificing the advantages of the invention as defined in the appended claims.

I claim: r

l. The combination with a variable displacement pump, of a distributing valve for directing the discharge therefrom, means operable to regulate pump displacement, fiuid actuated means for operating said valve, and means responsive to said displacement regulating means for controlling said valve operating means.

2. The combination with a variable displacement pump, of'a distributing valve for directing the discharge therefrom, means operable to regulate pump displacement, fluid actuated means for operating said valve, and a. pilot valve controlled by said displacement regulating means for controlling said fluid actuated means.

3. The combination with a variable displacemerit pump, of a distributing valve for directing the discharge therefrom, fluid actuated means 301' operating said valve, means including a rotatable shaft for regulating pump displacement, and a rotary valve actuated by said shaft for controlling said distributing valve.

4. The combination with a variable displacement pump, of a distributing valve for directing the discharge therefrom, means operable to regu- 4 late pump displacement, an auxiliary pump,

means actuated by said auxiliary pump for operating said valve, and means controlled by said displacement regulating means for controlling said valve operating means.

5. The combination with a variable displacement pump, of an auxiliary pump, valve mechanism operable to direct the discharge from said variable displacement pump and to add thereto the discharge from said auxiliary pump, fluid actuated means for operating said valve mechanism, means for regulating the displacement of said variable displacement pump, and means controlled by said last named means for controlling said valve mechanism.

6. The combination witha variable displacernent pump, of an auxiliary pump, valve mechanism operable to direct the discharge from said the discharge from said auxiliary pump, means for regulating the displacement of said variable displacement pump, and means actuated by said last named means for controlling said valve mechanism. 4

'7. The combination with a'variable displacement pump, of an auxiliary pump, a single valve movable to direct the discharge from said vari able displacement pump and to add thereto the discharge from said auxiliary pump, means "for regulating the displacement of said variable displacement pump, and means actuated thereby for controlling said valve.

8. The combination with a variable displacement pump, of an auxiliary pump, fluid actuated valve mechanism operable to connect the discharge from said auxiliary pump to the discharge from said variable displacement pump and to disconnect the same, means for regulating the displacement of said variable displacement pump,

and a pilot valve controlled by said displacement mechanism.

9. The combination with'a variable displacement pump, of an auxiliary pump, valve mechanism operable to connect the discharge from said auxiliary pump to the discharge from said variable displacement pump and to disconnect the same, means actuated by said auxiliary pump for operating said valve mechanism, means for regulating the displacement of said variable displacement pump, and a valve controlled by said last named means for controlling said valve mechanism.

10. The combination with a variable displacement pump, of an auxiliary pump, a multi-position valve for directing the discharge from said variable displacement pump and for connecting the discharge from said auxiliary pump thereto, a plurality of fluid actuated means for eflecting a step-by-step adjustment of said valve, means for regulating the displacement of said variable displacement pump, and means controlled by said last named means for controlling said fluid actuated means.

11. The combination, with a unidirectional tions from a central neutral position to vary pump displacement from zero to maximum without altering the direction of pump delivery, a distributing valve for directing the delivery of liquid discharged by said pump, and means responsive to the operation of said displacement varying means for operating said valve.

12. The combination, with a unidirectional variable displacement pump, of displacement varying means operable in either of two directions from a central neutral position to vary pump displacement from zero to maximum without altering the direction of pump delivery, a hydraulically actuated distributing valve for directing the delivery of liquid discharged by said pump, and a pilot valve responsive to the operation of said displacement varying means for controlling the operation of said distributing valve.

13. The combination, with a unidirectional. variable displacement pump, of displacement varying means operable in either of two directions from a central neutral position to vary pump displacement from zero to maximum without altering the direction of pump delivery, an auxiliary pump, a distributing valve for directing the delivery of liquid discharged by said variable pump and for adding thereto liquid discharged by said auxiliary pump, and means responsive to the operation of said displacement varying means for operating said valve.

14. The combination, with a unidirectional variable displacement pump, of displacement varying means operable in either of two directions from a central neutral position to vary pump displacement from zero to maximum without altering the direction of pump delivery, an auxiliary pump, a hydraulically actuated distributing valve for directing the delivery of liquid discharged by said variable pump and for adding thereto liquid discharged by said auxiliary pump, and a pilot valve responsive to the operation of said displacement varying means for controlling the operation of said distributing valve,

15. The combination, with a unidirectional variable displacement pump, of displacement varying means operable in either of two directions from a central neutral position to vary pump displacement from zero to maximum without altering the direction of pump delivery, an auxiliary pump, a hydraulically actuated distributing valve for directing the delivery of liquid discharged by said variable pump and for adding thereto liquid discharged by said auxiliary pump, hydraulic means operated by said auxiliary pump for operating said valve, and a pilot valve responsive to the operation of said displacement varying means for controlling the delivery of liquid to said hydraulic means.

WAL'IER FERRIS. 

